The motor minesweeper was a design by Richards Ironworks (
actually an experienced wooden shipbuilder ) for the clearing of
rivers and estuaries of acoustic and magnetic mines.
The piece of equipment which dictated the vessel's dimensions was
the 'Twin Longitudnal' ( LL ) wire sweep for dealing with
magnetic mines. It comprised of two bouyant copper cables 750
feet long unreeled from a large drum on the aft deck. A battery
bank ( charged by a 50kW generator ) pulsed a set current pattern
down these wires, creating a large magnetic field and thus
detonating magnetic mines. The vessel was obviously built of wood
to reduce magnetic signature, and the machinery was de-gaussed to
reduce the signature even further.
The other equipment carried was an acoustic 'hammer' on a large
A-frame fixed to the bows forward.
Post war, the MMS fleets were transferred to other navies to
allow them to sweep wartime mines from their own waters, and
because of their merchant lines and origins, it was the preffered
vessel to replenish the depleted fishing fleets ( more so than
the more military BYMS. )